High-energy shape memory polymer could someday help robots flex their muscles
When stretched or deformed, form memory polymers return to their first designs after heat or light-weight is utilized. These materials demonstrate terrific assure for delicate robotics, good biomedical equipment and deployable space structures, but until now they haven’t been in a position to retail outlet more than enough energy.
Now, researchers reporting in ACS Central Science have made a form memory polymer that merchants practically six instances more energy than prior variations.
An artificial muscle created of a stretched form memory polymer contracts upon heating, bending a mannequin’s arm. Graphic credit: Adapted from ACS Central Science 2021, DOI: 10.1021/acscentsci.1c00829
Shape memory polymers alternate among an first, undeformed point out and a secondary, deformed point out. The deformed point out is made by stretching the polymer and is held in put by molecular changes, such as dynamic bonding networks or pressure-induced crystallization, that are reversed with heat or light-weight. The polymer then returns to its first point out via the launch of stored entropic energy. But it’s been challenging for experts to make these polymers carry out energy-intense duties. Zhenan Bao and colleagues required to develop a new type of form memory polymer that stretches into a secure, very elongated point out, enabling it to launch huge amounts of energy when returning to its first point out.
The researchers integrated 4-,4’-methylene bisphenylurea models into a poly(propylene glycol) polymer spine. In the polymer’s first point out, polymer chains have been tangled and disordered. Stretching prompted the chains to align and variety hydrogen bonds among urea groups, creating supermolecular structures that stabilized the very elongated point out. Heating prompted the bonds to break and the polymer to deal to its original, disordered point out.
In checks, the polymer could be stretched up to 5 instances its first duration and retail outlet up to seventeen.nine J/g energy –– practically six instances more energy than prior form memory polymers. The staff demonstrated that the stretched materials could use this energy to carry objects five,000 instances its personal excess weight upon heating. They also created an artificial muscle by attaching the pre-stretched polymer to the higher and decrease arm of a wooden model. When heated, the materials contracted, leading to the model to bend its arm at the elbow. In addition to its history-higher energy density, the form memory polymer is also reasonably priced (uncooked materials value about $11 for every lb) and uncomplicated to make, the researchers say.
Source: acs.org
